1. Field of the Invention
The present application relates to an electrodeionization apparatus and method and, more particularly, to an electrodeionization apparatus and method incorporating an expanded conductive mesh electrode.
2. Description of Related Art
Electrodeionization (EDI) is a process that removes ionizable species from liquids using electrically active media and an electrical potential to influence ion transport. The electrically active media may function to alternately collect and discharge ionizable species, or to facilitate the transport of ions continuously by ionic or electronic substitution mechanisms. EDI devices may include media of permanent or temporary charge and may be operated to cause electrochemical reactions specifically designed to achieve or enhance performance. These devices also include electrically active membranes such as semipermeable ion exchange or bipolar membranes.
Continuous electrodeionization (CEDI) is a process wherein the primary sizing parameter is the transport through the media, not the ionic capacity of the media. A typical CEDI device includes alternating electroactive semipermeable anion and cation exchange membranes. The spaces between the membranes are configured to create liquid flow compartments with inlets and outlets. A transverse DC electrical field is imposed by an external power source using electrodes at the bounds of the membranes and compartments. Often, electrolyte compartments are provided so that reaction product from the electrodes can be separated from the other flow compartments. Upon imposition of the electric field, ions in the liquid are attracted to their respective counterelectrodes. The compartments bounded by the electroactive anion permeable membrane facing the anode and the electroactive cation membrane facing the cathode typically become ionically depleted and the compartments bounded by the electroactive cation permeable membrane facing the anode and the electroactive anion membrane facing the cathode typically become ionically concentrated. The volume within the ion-depleting compartments and, in some embodiments, within the ion-concentrating compartments, also includes electrically active media. In CEDI devices, the media may include intimately mixed anion and cation exchange resins. The ion-exchange media typically enhances the transport of ions within the compartments and may participate as a substrate for controlled electrochemical reactions.
The present invention is directed to an electrodeionization apparatus comprising at least one electrode formed from an expanded conductive mesh in contact with an ion-permeable membrane.
In another embodiment, the present invention is directed to an electrodeionization apparatus comprising an electrode and an ion-permeable membrane comprising a perfluorosulfonic acid and positioned adjacent the electrode.
In another embodiment, the present invention is directed to an electrodeionization apparatus comprising an electrode and an ion-permeable membrane comprising a copolymer of polytetrafluoroethylene and perfluorosulfonic acid and positioned adjacent the electrode.
In another embodiment, the present invention is directed to an electrodeionization apparatus comprising an expanded mesh electrode positioned between at least two spacers.
In another aspect of the present invention, an electrodeionization apparatus is provided comprising at least one electrode formed from an expanded conductive metal mesh wherein a first surface of the electrode is in contact with an ion-permeable membrane and an opposing surface of the electrode is in contact with an endblock.
In another aspect of the invention, an electrodeionization apparatus comprises an ion-depleting compartment, an anolyte compartment comprising an expanded titanium mesh anode in contact with an ion-permeable membrane and a catholyte compartment.
In another aspect of the present invention, an electrodeionization apparatus is provided comprising a plurality of alternating anion and cation permeable membranes that define ion-depleting and ion-concentrating compartments, an anolyte compartment comprising an expanded metal mesh anode in contact with an anion-permeable membrane and a catholyte compartment.
In another aspect of the present invention, an electrodeionization apparatus is provided comprising at least one electrode formed from an expanded metal mesh in contact with an interior surface of an endblock wherein the interior surface comprises flow channels.
In another aspect of the invention, a method of purifying a liquid comprises the steps of providing an electrodeionization apparatus comprising at least one electrode formed from an expanded metal mesh, wherein the electrode is in contact with an ion-permeable membrane, applying an electrical current across the electrodeionization apparatus and passing the liquid through the electrodeionization apparatus.
In another aspect of the invention, a method of purifying a liquid comprises the steps of providing an electrodeionization apparatus comprising at least one electrode formed from an expanded metal mesh, wherein a first surface of the electrode is in contact with an ion-permeable membrane and an opposing surface of the electrode is in contact with an inner surface of an endblock wherein the inner surface comprises flow channels, applying an electrical current across the electrodeionization apparatus and passing the liquid through the electrodeionization apparatus.
In another aspect of the invention, a method of purifying a liquid comprises the steps of providing an electrodeionization apparatus comprising at least one electrode formed from an expanded metal mesh, wherein a first surface of the electrode is in contact with an ion-permeable membrane and an opposing surface of the electrode is in contact with an inner surface of an endblock wherein the inner surface comprises flow channels, applying an electrical current across the electrodeionization apparatus, promoting fluid mixing in a region adjacent the electrode and passing the liquid through the electrodeionization apparatus.
In another aspect of the invention, a method of purifying a liquid comprises the steps of providing an electrodeionization apparatus comprising an ion-depleting compartment, an anolyte compartment and a catholyte compartment, wherein the anolyte compartment comprises an expanded titanium mesh anode in contact with an ion-permeable membrane, applying an electrical current across the electrodeionization apparatus and passing the liquid through the electrodeionization apparatus.
In another aspect of the invention, a method of purifying a liquid comprises providing an electrodeionization apparatus comprising alternating anion and cation permeable membranes defining ion-depleting and ion-concentrating compartments, an anolyte compartment and a catholyte compartment, wherein the anolyte compartment comprises an expanded metal mesh anode, applying an electrical current across the electrodeionization apparatus and passing the liquid through the electrodeionization apparatus.
In another embodiment, the present invention is directed to an electrodeionization apparatus comprising an electrode compartment constructed and arranged to allow purification of a liquid without chemical addition to provide a reduction in electrical resistance across the compartment.
In another embodiment, the present invention is directed to an electrodeionization apparatus comprising an electrode compartment free of ion exchange resin constructed and arranged to allow purification of a liquid without chemical addition to provide a reduction in electrical resistance across the compartment.
In another embodiment, the invention is directed to an electrodeionization apparatus comprising an electrode compartment free of ion exchange resin and constructed and arranged to allow purification of liquid without chemical addition to provide a substantially uniform current density in the compartment.
In another embodiment, a method is provided for purifying a liquid comprising the steps of providing an electrodeionization apparatus comprising an electrode formed from an expanded conductive mesh, wherein the electrode is in contact with an ion-permeable membrane comprising perfluorosulfonic acid, applying an electrical current across the electrodeionization apparatus and passing the liquid through the electrodeionization apparatus.
In another embodiment, a method is provided for purifying a liquid comprising the steps of providing an electrodeionization apparatus comprising an electrode formed from an expanded conductive mesh, wherein a first surface of the electrode is in contact with an ion-permeable membrane comprising a copolymer of perfluorosulfonic acid and polytetrafluoroethylene and an opposing surface of the electrode is in contact with an inner surface of an endblock wherein the inner surface comprises liquid flow channels, applying an electrical current across the electrodeionization apparatus and passing the liquid through the electrodeionization apparatus.
In another aspect of the present invention, an electrodeionization apparatus is provided comprising at least one electrode formed from a perforated plate positioned adjacent to an ion-permeable membrane.
In another aspect of the present invention, an electrodeionization apparatus is provided comprising an electrode positioned adjacent a flow mixer.
In another aspect of the present invention, an electrodeionization apparatus is provided comprising an expanded mesh electrode, a spacer positioned adjacent the mesh electrode and an ion-permeable membrane positioned adjacent the mesh electrode at an opposite side from the spacer.
In another embodiment, the present invention is directed to an electrodeionization apparatus comprising at least one electrode formed from an expanded mesh positioned adjacent to an ion-permeable membrane.